1. Field of the Invention
The present invention relates to miniature, micromachined valves which provide reduced fluid volume in the valve and are useful for gas chromatography.
2. Description of the Prior Art
In the prior art various miniature, micromachined valves have been advanced. The valves are made using chemical etching or micromachining techniques for forming passageways in single crystal silicon wafers which are then bonded into a sandwich or layered construction. The valves are generally opened and closed by actuating a silicon deflecting diaphragm, usually by electrostatic control or by fluid pressure actuation. Miniaturization is desired, but if the diaphragm size is reduced substantially, the stress levels in the diaphragm become excessively high when the diaphragm is actuated sufficiently to fully open the valves, particularly when silicon is used. The absence of a relatively flexible, low stress level material that can be utilized as a diaphragm and which will withstand the hostile environment in which the valves operate has limited the reduction in size of the valves. Deflections in the range of 0.002 to 0.003 inch (50-75 microns) must be achieved without overstressing the diaphragms. The present invention relates to a batch fabricated, sandwich construction valve utilizing silicon, glass or other suitable material wafers that are micromachined or molded to form necessary ports and channels, and a diaphragm film between two wafers for actuating the valves formed in the layers.